The invention relates to a reproduction apparatus which is provided for reproducing data stored along at least one track on a rotary drivable optically readable data carrier and which includes drive means which are arranged for receiving a drive signal and for driving the data carrier in accordance with the received drive signal, and which includes reading means which are arranged for reading the stored data and for delivering the read data and which includes drive control means which are arranged for receiving and evaluating the read data and for generating and delivering a controlled drive signal while the read data are used, to enable the data carrier to be driven in accordance with the controlled drive signal, and which includes detection means with whose help there may be detected whether read data suitable for generating the controlled drive signal are available and which are arranged for delivering a detection signal when such suitable data are lacking.
Such a reproduction apparatus of the type in accordance with the opening paragraph has been developed by the applicants and is marketed as a so-called CD player referred to as CD753 and is therefore known.
With the known reproduction apparatus there is the problem that a reproduction of data stored on a writable CD is absolutely impossible while the CD has not yet been brought to a finalized state. The CD in the non-finalized state has useful data in a useful data area, which in the present case represent at least a piece of music and additional data. Furthermore, the CD has a first contents data area in which contents data are temporarily stored, which represent a temporary table of contents about the at least one piece of music stored in the useful data area. The first contents data area is spatially separated from the useful data area on the CD. With a finalization, the contents data are read from the first contents data area and stored in the second contents data area, in which second contents data area the contents data are permanently stored and thus represent a final table of contents.
With a newly inserted CD the known reproduction apparatus first verifies whether there are useful data at all in the useful data area of the CD and, after a successful test, tries to read the contents data from the second contents data area, thus the final table of contents. The second contents data area, however, with a non-finalized CD, does not yet contain any contents data. In the known reproduction apparatus, the detection means establish in a completely unrecorded, thus non-finalized CD, that no useful data are read out from the useful data area. With an only partly recorded and thus non-finalized CD there is established that useful data are read from the useful data area, it is true, but after that no contents data are read from the second contents data area. Due to the lacking of the useful data in the former case and due to the lacking of the contents data in the latter case, the circumstances are that there are no data available for generating the controlled drive signal. In the known reproduction apparatus this causes parts of the reproduction apparatus to be deactivated and a warning to be generated which signals a supposed error, which does not correspond to reality and which is therefore not satisfactory for a user.
There may be observed that it is known from other reproduction apparatus that means are provided with the aid of which the useful data can be read from the useful data area of the non-finalized CD and a virtual table of contents of the non-finalized CD can be provided. These reproduction apparatus, however, have serious disadvantages, because with these means a distinction cannot be made between useful data in the useful data area, which are featured as deleted in the temporary table of contents, and useful data in the useful data area, which are featured as valid in the temporary table of contents. Furthermore, an end of new useful data in the useful data area with which old useful data in the useful data area are overwritten cannot safely be removed. Reading the useful data from the useful data area may be a lengthy operation under certain circumstances and finding the end of the useful data area may be linked with great difficulty. Therefore, these means lead to highly unreliable results, which are also highly unsatisfactory for the user of such a reproduction apparatus.
It is an object of the invention to resolve the problems defined above with a reproduction apparatus of the type defined in the opening paragraph and provide an improved reproduction apparatus, so that even in the case of a non-finalized data carrier, the temporary table of contents can be reliably found and read in the first contents data area and that thus the useful data in the useful data area of a non-finalized data carrier and of a finalized data carrier can be reproduced for a user without any problems and in a satisfactory manner.
The object defined above is achieved with a reproduction apparatus of the type defined in the opening paragraph, in that additional drive control means are provided which are arranged for generating and delivering a controlled drive signal, and in that control means are provided which are arranged for receiving the detection signal and which, as a result of receiving the detection signal, enable to drive the data carrier in accordance with the controlled drive signal.
Providing the characteristic features in accordance with the invention achieves in an advantageous manner that also when non-written areas of the data carrier are scanned, in which areas no data suitable for generating the controlled drive signal are stored, the data carrier is enabled to be driven at a constant angular velocity determined by the controlled drive signal, so that even when these areas of the data carrier are scanned, the angular velocity of the data carrier always remains within a suitable range, although no expensive electronics and no high-price optics are provided as are necessary for an evaluation of control information contained in a control track of the data carrier. Furthermore, the great advantage is achieved that first a temporary table of contents of a non-finalized data carrier is made possible with very simple means, which is in contrast to so-called CD writers already known, in which finding a temporary table of contents is possible, it is true, but at incomparably higher cost.
Providing the characteristic features as claimed in claim 2 achieves in an advantageous manner that both the regulated drive signal and the controlled drive signal can be sent over the single line to the drive means, so that additional lines and additional terminals for these additional lines may be omitted, which in turn leads to a reduction of the number of potential error sources. Furthermore, the advantage is obtained that it is only necessary to turn off at least one output of the drive regulating means to enable the data carrier to be driven in accordance with the controlled drive signal.
By providing the characteristic features as claimed in claim 3, there is achieved in an advantageous manner that an extremely simple embodiment of the switching means is made possible which, in turn, makes a contribution to realizing the switching means in a most cost-effective manner. Furthermore, the advantage is obtained that the cost of circuitry is kept lowest possible.
By providing the characteristic features as claimed in claim 4, there is achieved in an advantageous manner that the drive control means are arranged in an extremely simple manner and can therefore also be realized in an extremely cost-effective manner.
By providing the characteristic features as claimed in claim 5, there is achieved in an advantageous manner that the table of contents of a data carrier can be found and thereafter read in an extremely reliable and also fast manner.
The aspects defined above and further aspects of the invention will be apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment.